Una búsqueda de compañeros de estrellas Luyten con el Observatorio Virtual

A search for companions to Luyten stars with the Virtual Observatory

José A. Caballero1

F. Xavier Miret2

Joan Genebriera3

Tófol Tobal2

Jordi Cairol2

David Montes1

1: Dpto. de Astrofísica, Universidad Complutense de Madrd2: Observatori Astrònomic del Garraf, Barcelona3: Observatorio de Tacande, La Palma

Albus 1 (Caballero & Solano 2007, ApJ, 665, L151)

Serendipitous discovery of a very bright white dwarf candidate...

...that is actually one of the brightest He-B subdwarfs

(Vennes, Kawka & Smith 2007, ApJ, 668, L59;

A. Ulla et al. in prep.)

Koenigstuhl 1 AB (Caballero 2007a, A&A, 462, L61)

The (second) widest ultracool binary: a challenge for very low-mass formation ejection scenarios!

Seven astrometric epochs since 1977.6 until 2004.0:

= 77.76(7) arcsec

d = 23(2) pc

r = 1800(170) AU MA = 0.103(6) Msol

MB = 0.079(4) Msol

Koenigstuhl 2 AB (Caballero 2007d, ApJ, 667, 520)

A new very low-mass star in a wide binary: the third widest system with MA + MB < 0.4 Msol

(in a draw)

Primary: LP 655-23(Luyten 1979)

Secondary: 2M0430-08 (M8.0V; Cruz et al. 2003)

r = 450(40) AU MA = 0.26(4) Msol

MB = 0.086(4) Msol

Koenigstuhl 3 ABC (Caballero 2007d, ApJ, 667, 520)

The widest system containing an L dwarf component

Primary: HD 221356(F8.0V; Hipparcos)

Secondary: 2M2331-04AB (M8.0V+L3.0V; Gizis et al. 2000, 2003)

= 7.530(7) arcmin !

r = 11900(300) AU MA = 1.02(7) Msol

MBC = 0.088+0.072 Msol

And Koenigstuhl 4 AB is coming!

(Caballero, in prep.)

Frequency of wide multiples with late-type (>M5) components: 5.0

± 1.8 %

The Garraf survey:an Aladin-based search for common-, high-proper motion pairs

• The New Luyten Two Tenths (NLTT) catalogue (Luyten 1979), > 0.2 arcsec a-1

• Improved astrometry in Salim & Gould (2003): 36 000 stars

• Selection: proper motions between 0.5 and 1.0 arcsec a-1

• Still 1947 stars!

• Using Aladin instead of SuperCOSMOS Science Archive

Still a lot of work one person...

Help #1:Xavier, Tófol and Xavier at the Observatori Astrònomic del Garraf

OAG (1976): a non-proffesional centre dedicated to the study of visual double stars

OAG revised the Comellas’ 1973.0 and 1980.0 catalogues and coordinated most of non-proffesional observations of doubles in Spain from 1990 to 2003

OAG is one the main measurement providers of the USNO Washington Double Stars catalogue (104)

The Garraf survey:Methodology

• Data loading and cross-matching: USNO-B1+2MASS

• Proper-motion diagram and candidate selection

• Recovery of known pairs with incorrect USNO-B1 proper motions with the “proper motion filter”

• One-by-one inspection of all selected binary candidates (SIMBAD, CCDM, Tycho-2...)

The Garraf survey:Current status

• ~160 common- candidate companions studied to date

• 86 rejected systems with bad USNO-B1 astrometry

• 8 pairs with different USNO-B1 proper motions

• 20 physical systems with both star components in Hipparcos

• 29 physical systems with only one star component in Hipparcos

• 19 physical systems with no components in Hipparcos

• Half a dozen new serendipitously-discovered physical systems

Help #2:The Tacande astro-photometric follow-up

A battery of “small” telescopes in La Palma: 40, 20, 15, 12, 9 cm

• 40 cm Cassegrain Relay, F6/5, with a CCD ST8XE

Garraf 1AB:An example of serendipitous discovery...

A: G 125-15, M4.5e, X-ray, variable, age ~ 300 Ma (Daemgen et al. 2007)

B: G 125-14, M5.5?

Known binary in Giclas et al. (1971)

Garraf 1AB:A bright, young, very wide, low-mass binary in the solar neighbourhood

Multi-epoch relative astrometry:

1952 Jul 17 POSSI Red

1988 Jun 13 POSSII Blue

1992 Aug 31 POSSII Red

1993 Jun 13 POSSII Infrared

1998 Jun 01 2MASS

2001 Aug 26 CMC14

2008 Mar 07 Tacande

Age? = 46.0 ± 0.3 arcsec

= 347.34 ± 0.16 degd = 17+6

-5 pcr = 800+300

-200 AUMA = 0.21+0.08

-0.05 Msol

MB = 0. 12+0.04-0.03 Msol

Help #3:Optical imaging and low-resolution spectroscopy of Garraf 1AB with CAFOS / 2.2 m by David Montes

M4.5e + M5.0:e. Accurate BVRI magnitudes. New astrometric epoch (2008 Apr 30)

Conclusions

A search for companions to Luyten stars with the Virtual Observatory

What will be a trained investigator be able do with SDSS + UKIDSS + LSST + GAIA...?